package cn.weixin.mp.aes;


import org.bouncycastle.jce.provider.BouncyCastleProvider;  
import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Security;


import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;


public class AES {
public static boolean initialized = false;    
    
    /** 
     * AES解密 
     * @param content 密文 
     * @return 
     * @throws InvalidAlgorithmParameterException  
     * @throws NoSuchProviderException  
     */  
    public static byte[] decrypt(byte[] content, byte[] keyByte, byte[] ivByte) throws InvalidAlgorithmParameterException {  
        initialize();  
        try {  
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");  
            Key sKeySpec = new SecretKeySpec(keyByte, "AES");  
              
            cipher.init(Cipher.DECRYPT_MODE, sKeySpec, generateIV(ivByte));// 初始化   
            byte[] result = cipher.doFinal(content);  
            return result;  
        } catch (NoSuchAlgorithmException e) {  
            e.printStackTrace();    
        } catch (NoSuchPaddingException e) {  
            e.printStackTrace();    
        } catch (InvalidKeyException e) {  
            e.printStackTrace();  
        } catch (IllegalBlockSizeException e) {  
            e.printStackTrace();  
        } catch (BadPaddingException e) {  
            e.printStackTrace();  
        } catch (NoSuchProviderException e) {  
            e.printStackTrace();  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
        return null;  
    }    
      
    public static void initialize(){    
        if (initialized) return;    
        Security.addProvider(new BouncyCastleProvider());    
        initialized = true;    
    }  
    //生成iv    
    public static AlgorithmParameters generateIV(byte[] iv) throws Exception{    
        AlgorithmParameters params = AlgorithmParameters.getInstance("AES");    
        params.init(new IvParameterSpec(iv));    
        return params;    
    }     


}